John 14 devotes itself much to the Holy Spirit.
Jesus says he will send the Holy Spirit after his death (going away). The Holy Spirit is the Paraclete, Advocate, Counselor, Helper and Comforter.
Thus Holy Spirit can be our ‘lawyer’ and a comforter as well. In other word, He speaks for us.
What is He speaking for us? In the case for the apostles, it was about being witnesses for Jesus. What can they say about Jesus? Here, the Holy Spirit would speak for them. We see how Peter spoke about Jesus, the resurrection and what people should do. Peter spoke when he was interrogated by the priests or to the crowd.
We are called to be witnesses, and the Holy Spirit speaks for us and convicts our hearts. That we are sinners and therefore need Jesus.
The other aspect of the Holy Spirit is as a comforter. I guess this is the aspect of where the Holy Spirit ministers to us, or to the people through us as His instruments.
God bless.